Workover operations are provided on existing production wells for various reasons. Several well workovers require a series of separate steps or tasks. Some of the steps may involve the insertion of coiled tubing (CT) downhole through the production tubing string, and then the lifting or pulling of the production tubing string. For example, it may be desired to raise the level of the producing zone one hundred (100) feet, for example, above the old producing zone and remove sand from the production tubing. For this purpose, coiled tubing (CT) is inserted within the production tubing by an injector for cleaning the sand from the tubing. Then the CT and CT injector are removed from the production tubing string. Next, a pipe pulling device or structure is mounted over the well for pulling or lifting the production tubing string to the desired height for raising the production zone. The upper end of the production tubing string after being raised is normally removed. Several types of pulling devices may be utilized with a coiled tubing injector as indicated below.
Drilling Rig and Standard Coiled Tubing Unit
The use of a drilling rig and a standard coiled tubing unit is not a standard practice for workover operations. However, the combination is possible and has application in some cases. The drilling rig is used to manipulate the jointed pipe while the coiled tubing unit runs the coiled tubing.
In this method the drilling rig manipulates the pipe in the wellbore to achieve the required task. Pipe which is removed from the well is either racked on the rig or laid down on the pipe rack. When continuous coiled tubing is needed the CT injector is moved on the rig floor and suspended from the traveling block of the rig. The coiled tubing system is then rigged up and the job performed. At the conclusion of the CT operation the injector is removed from the rig floor and rig operations proceed as needed. This exchange of equipment cycles back and forth until the planned intervention is completed.
Pulling Unit and Standard Coiled Tubing Unit
The use of the pulling unit and a standard coiled unit is a standard practice for workover operations. On jobs using a pulling unit and a standard coiled tubing unit, the pulling unit is used to manipulate the jointed pipe while the coiled tubing unit is used to run coiled tubing.
In this method using a large pulling unit, pipe is manipulated in the wellbore to achieve the required task by the pulling units. Pipe which is removed from the well is either racked on the rig or laid down on the pipe rack. When continuous coiled tubing is needed the CT injector is moved onto the rig floor and suspended from the traveling block of the pulling unit. The coiled tubing system is then rigged up and the job performed. At the conclusion of the CT operation the injector is removed from the rig floor and pulling unit operations proceed as needed. This exchange of equipment cycles back and forth until the planned intervention is completed.
For smaller pulling units, pipe which is removed from the well is laid down on the pipe rack. When continuous coiled tubing is needed the pulling unit is moved away from the well. The CT injector is moved over the wellhead and suspended from a crane. The coiled tubing system is then rigged up and the job performed. At the conclusion of the CT operation the injector is removed from the well and its pulling unit is moved back onto the well. This exchange of equipment cycles back and forth until the planned intervention is completed.
Snubbing Unit and Standard Coiled Tubing Unit
The use of a snubbing unit and a standard coiled tubing unit is a standard practice for workover operations. On jobs using a snubbing unit and a standard coiled unit, the snubbing unit is used to manipulate the jointed pipe while the coiled tubing unit is used to run coiled tubing.
In this method, pipe is manipulated in the wellbore to achieve the required task by the snubbing unit. The snubbing unit jacks pipe out or into the well with a series of short (5-15 feet) strokes. Pipe which is removed from the well is laid down on a pipe rack. When continuous coiled tubing is needed the CT injector is moved onto the rig floor and suspended from a crane. The coiled tubing system would then be rigged up and the job performed. At the conclusion of the CT operation the injector is removed from the rig floor and snubbing unit operations proceed as needed. This exchange of equipment cycles back and forth until the planned intervention is completed.
In many cases a snubbing unit rig up is very tall. In many cases the snubbing unit is moved away from the well and the CT unit is suspended over the wellhead with a crane to perform the job. At the conclusion of the CT operation the injector would be removed from the well and the snubbing unit would be moved back onto the well. This exchange of equipment would cycle back and forth until the planned intervention was completed.
Jack-up Frame and Standard Coiled Tubing Unit
The use of a jacking frame and a standard coiled tubing unit is a standard practice for workover operations. On jobs using a jacking frame and a standard coiled tubing unit, the jacking frame is used to manipulate the jointed pipe while the coiled tubing unit is used to run coiled tubing.
In this method, pipe is manipulated in the wellbore to achieve the required task by the jacking frame. The jacking frame jacks pipe out of or into the well with a series of short (5-10 foot) strokes. Pipe which is removed from the well is laid down on a pipe rack. When continuous coiled tubing is needed the CT injector is moved onto the jacking frame floor. The coiled tubing system is then rigged up and the job performed. At the conclusion of the CT operation the injector is removed from the floor and jacking frame operations would proceed as needed. This exchange of equipment cycles back and forth until the planned intervention is completed.
The limitation of all of these methods is that the coiled tubing injector must be rigged up and rigged down repeatedly to complete a job. This invention addresses this requirement and makes the operation more efficient. For the methods using a drilling rig, pulling unit or snubbing unit, a second contractor and additional assets are also required which make a project more difficult to manage and more expensive in terms of costs.